Certain arylthioureas have been disclosed as useful for the treatment of helminth infections in mammals. For example, U.S. Pat. No. 3,659,012 issued Apr. 25, 1972 to Porter et al., discloses that particular 1,1,3-trisubstituted thioureas are anthelmintic agents. Ticarbodine (.alpha.,.alpha.,.alpha.-trifluoro-2,6-di(methyl)thio-1-piperidinecarboxy- m-toluide), has the structural formula ##STR2## and has been reported to have a high degree of anthelmintic efficacy; see Am. H. Vet Res., 33 (4):709 (1972).
It has now been found that certain phenylene-bis[substituted thioureas] have anthelmintic activity.